Rotor shaft for use in an aerating device

ABSTRACT

Rotor shaft ( 22 ) for use in an aerating device ( 1 ) for a ground, wherein the rotor shaft ( 22 ) comprises at least one connecting disc ( 4 ) which extends transversely of the axis of the rotor shaft ( 22 ) and on which at least two knives ( 3 ) are arranged, wherein each knife ( 3 ) is provided with two knife connecting holes ( 33   a,    33   b ) and is connected between the connecting disc ( 4 ) and a connecting ring ( 6 ), wherein the connecting disc ( 4 ) and the connecting ring ( 6 ) are provided with knife connecting holes ( 44, 54 ) which coincide with the knife connecting holes ( 33   a,    33   b ) of the knives ( 3 ), wherein bolts ( 74 ) are arranged through the coinciding knife connecting holes ( 33   a,    33   b ) in order to connect the connecting disc ( 4 ), the knives ( 3 ) and the connecting ring ( 6 ), wherein the connecting ring ( 6 ) is constructed from at least two ring sectors which together form the connecting ring ( 6 ).

The present invention relates to a rotor shaft for use in an aeratingdevice for a ground, wherein the rotor shaft comprises at least oneconnecting disc which extends transversely of the axis of the rotorshaft and on which at least two knives are arranged, wherein each knifeis provided with two knife connecting holes and is connected between theconnecting disc and a connecting ring, wherein the connecting disc andthe connecting ring are provided with knife connecting holes whichcoincide with the knife connecting holes of the knives, wherein boltsare arranged through the coinciding knife connecting holes in order toconnect the connecting disc, the knives and the connecting ring. Theinvention also relates to an aerating device provided with such a rotorshaft.

For the purpose of aerating a ground, particularly a ground providedwith a grass cover, it is known to arrange slits in this ground using anaerating device provided with a rotor shaft on which knives arearranged. As the device advances over the ground the knives arranged onthe rotating shaft are carried successively into the ground and formslits therein. Such slits have a positive effect on the grass cover.

A typical rotor shaft is provided here with a number of connecting discsarranged fixedly on the shaft, i.e. substantially without play. Arrangedon these discs are several knives, for instance two, more often three,protruding beyond the peripheral edges of these discs. The knives herealso lie roughly transversely of the axis of the rotor shaft and arearranged at regular positions on the disc so that they are evenlydistributed over the peripheral edge.

The knives are arranged on the connecting disc using a connecting ring.Such a connecting ring has an outer periphery roughly corresponding tothe periphery of the connecting disc so that they can as it were beplaced one onto the other. The knives are placed here between theconnecting disc and the connecting ring, wherein the disc and the ringas it were clamp the knives. The knives are generally provided with anouter end taking a flat form in which at least two knife connectingholes are arranged. Just as the connecting ring, the connecting disc isalso provided close to the peripheral edge with corresponding connectingholes. Inserted through the coinciding holes of the ring, the knives andthe disc are bolts onto which nuts are screwed. A firm connection isthus obtained, wherein it is even possible to replace a knife shouldthis be necessary.

The rotor shaft is after all rotated at high speed so that the forces onthe knives are also great. It is not therefore unusual for a knife to bedamaged, for instance by a rock in the ground. The bolts and nuts of theassociated knife can then be loosened, after which the knife can beremoved from between the connecting disc and the connecting ring and bereplaced.

If the connecting ring is however also damaged, for instance deformed,it is then very difficult, if not impossible, to repair the rotor shaft.The present invention has for its object, among others, to at leastpartially obviate this problem.

The rotor shaft of the type stated in the preamble has for this purposethe special feature that the connecting ring is constructed from atleast two ring sectors which together form the connecting ring. If theconnecting ring, i.e. one or even more of the ring sectors, is nowdamaged it can be easily removed by removing the bolts of the relevantring sector(s). A damaged sector can then be taken off the connectingdisc and rotor shaft and replaced in simple manner. In the case that acontinuous ring is used this is more difficult, particularly whendifferent discs are arranged on the shaft. The discs on the shaft canthen block removal of the ring, while placing of a new ring is notpossible either. The shaft will in that case therefore have to bedisassembled. This problem is solved by constructing the connecting ringof the rotor shaft, or rotor shaft assembly, from different, i.e.separate, ring sectors which together form a connecting ring in thecoupled state.

For the sake of clarity the term ring sector must be understood to meanthe form of a ring enclosed between two radii from the centre. Aplurality of connected ring sectors form a ring here. Although the outerends of the ring sectors, i.e. the edges between the two circular arcs,can be embodied straight and parallel to the radii, this is notessential. It is however advantageous for the outer ends of two ringsectors to take a complementary form so that they fit closely in theconnected state. This provides for a good force transmission. Theconnecting ring, i.e. the ring sectors, preferably takes a plate-likeform.

According to a preferred embodiment the ring sectors are uniform. Inother words, the ring sectors all have the same shape. This enables easyreplacement of the components if necessary.

According to a further preferred embodiment of the rotor shaft, eachring sector is provided close to the outer ends with a knife connectinghole, wherein a ring sector is connected to two knives and extendstherebetween. Each knife is therefore simultaneously connected to tworing sectors. In the case of damage or deformation of one ring sector aknife is still held by another ring sector, this enhancing reliabilityand safety.

For the purpose of a good angle of incidence of the knives into theground it is advantageous for the knife connecting holes of, or for, asingle knife to be located at different radial distances. In orderhowever to limit the size of the connecting ring here in radialdirection a ring sector can be provided with at least one protrusion foraccommodating a knife connecting hole. The first knife connecting holecan for instance extend close to the inner periphery of the ring sector,while the second knife connecting hole extends close to the outerperiphery, wherein the protrusion is arranged for strengtheningpurposes. It is for instance possible for the knife connecting hole tobe arranged at least partially in the protrusion.

As stated, the outer ends of the knives, in which the knife connectingholes are also arranged, are situated between the connecting disc andthe connecting ring, which is constructed according to the inventionfrom a plurality of ring sectors. Now that the knives do not extend overthe whole peripheral edge of the disc and the ring, there are spacesbetween the knives. In order to fill these spaces a further preferredembodiment of a rotor shaft according to the invention further comprisesring sector-shaped filling members between the knives, wherein a fillingmember has a form such that on the one hand it fills the space betweenthe connecting disc and the connecting ring as seen in a directiontransversely of the plane of the connecting disc and on the other thespace between two knives as seen in a direction parallel to the plane ofthe connecting disc. A filling member has the same thickness here, i.e.as seen in the direction of the axis of the rotor shaft, as thethickness of the outer end of the knife so that the transition from theknife to a tilling member is smooth. The connecting ring can then bearranged thereon. In the plane of the connecting disc the form isdefined by the contours of the knives so that the filling members liefirmly against the knives in the connected state. The two outer ends ofa filling member preferably take a form here complementary to that ofthe knives.

According to a further preferred embodiment, a filling member isprovided with at least one filling member connecting hole and whereinthe connecting ring and connecting disc are provided with filling memberconnecting holes which coincide with the filling member connecting holesof the filling members, wherein bolts are arranged through thecoinciding filler piece connecting holes in order to connect theconnecting disc, the filling members and the connecting ring. Thefilling members are embodied here as separate, i.e. releasable,components so that they can also be exchanged in simple manner in caseof damage. A strong assembly is obtained when the connecting ringoverlaps the filling members in the connected state.

It has moreover been found that the use of separate filling memberswhich can be attached using bolts and nuts makes the rotor shaft betterable to withstand the high peak forces during use. Each filling memberis preferably provided with a plurality of filling member connectingholes, for instance two or three, so that possible torsion of thefilling members is counteracted. The filling member connecting holespreferably lie at equal radial distances relative to the centre of theconnecting disc.

In this embodiment the connecting disc is therefore provided with pairsof knife connecting holes close to the peripheral edge for the purposeof connecting knives, wherein at least one, preferably two or three,filling member connecting holes are arranged between each of these pairsof knife connecting holes for the purpose of arranging the fillingmembers between the knives.

It must be noted that it is also possible to apply the filling membersas described above in a rotor shaft, wherein the connecting ring isembodied as a single ring, so without the use of the ring sectors. Theadvantages of efficient exchange of the filling members and the betterforce transmission are also achieved in such an embodiment.

It is recommended however that the connecting ring is also constructedfrom separate ring sectors as described. A ring sector is then providedwith a tilling member connecting hole coinciding with a tilling memberconnecting hole of a tilling member. As stated, it is recommended that aring sector connects two knives so that a ring sector extends over twoknives so that it partially overlaps them. The filling member is thenarranged between these knives as seen in the plane of the connectingdisc, and therefore between the connecting disc and this ring sector asseen in a direction transversely of the plane of the connecting disc. Aring sector preferably overlaps a filling member almost wholly.

According to a further preferred embodiment, the filling members and theknives form a continuous annular structure in the connected state. Thisresults in a stable assembly, wherein play between the knives and theconnecting disc, the filling members and the connecting ring isprevented as far as possible. It is advantageous here for the knives tobe held in form-fitting manner between the filling members, theconnecting disc and the connecting ring.

In order to further improve the connection between knife and rotor shaftand to reduce the chance of play it is advantageous for a knife to beprovided with a recess which forms a contact surface with a normal witha component in the radial direction, wherein a filling member isprovided with a projection with a form complementary to the contactsurface of the recess. The recess is preferably located at the outermostend of the knife It is moreover advantageous for a good fit for theprojection to be arranged at an outer end of a filling member.

According to a further preferred embodiment, the filling memberconnecting holes have a diameter differing from that of the knifeconnecting holes. The diameters of the knife connecting holes arepreferably larger since the forces on these connections are greater. Theuse of different diameters moreover makes the assembly of the rotorshaft simpler since it is immediately apparent which hole serves whichpurpose.

The invention further relates to an aerating device for a ground,comprising:

-   -   a frame;    -   moving means arranged on the frame for the purpose of moving the        aerating device in a direction of movement over a surface for        working;    -   a drive;    -   a rotor shaft according to the invention operatively connected        to the drive for the purpose of rotating the rotor shaft.

An aerating device provided with a rotor shaft as described above isefficient in use since in the case of possible damage to components,such as a knife or the connecting ring, these components can preferablybe replaced in simple manner on site.

A preferred embodiment of the aerating device further comprises ahousing which protects at least the rotor shaft, wherein the housing isprovided with a hatch which is arranged hingedly on the housing for thepurpose of making the rotor shaft accessible. The hatch is then movablebetween an opened position, in which the rotor shaft with knives isaccessible or even removable, and a closed position in which the hatchtogether with the housing protects the rotor shaft. Opening the hatchmakes the rotor shaft accessible so that components can be replaced ifnecessary. Complete disassembly of the housing or the removal of partsof this housing is then not necessary.

The invention also relates to a ring sector and a ring sector-shapedfilling member for use in a rotor shaft according to the invention.

The invention further relates to a rotor shaft for use in an aeratingdevice for a ground as such, wherein the rotor shaft comprises at leastone connecting disc which extends transversely of the axis of the rotorshaft and in which pairs of knife connecting holes are arranged close tothe peripheral edge at equal distances from each other, and wherein atleast one filling member connecting hole is arranged between the pairsof knife connecting holes. The filling member connecting hole morepreferably has a diameter differing from that of the knife connectingholes. A plurality of filling member connecting holes are preferablyarranged between the knife connecting holes.

The present invention is further illustrated with reference to thefollowing figures, which show a preferred embodiment of the deviceaccording to the invention and are not intended to limit the scope ofthe invention in any way, wherein:

FIG. 1 is a perspective view of an aerating device;

FIG. 2 is a schematic perspective view of the rotor shaft according tothe invention;

FIG. 3 is a schematic side view of the relation between the fillingmembers and the knives, and

FIG. 4 is a schematic side view of the connecting disc of FIG. 3 witharranged ring parts.

FIG. 1 shows an aerating device 1 provided with a frame 16, moving meansembodied as travel roller 11 and a drive embodied as transmission 14 inwhich a power take-off of a tractive vehicle can be arranged. Device 1can be connected to a tractive vehicle using an attachment 15. Connectedto transmission 14 is a rotor shaft 2 which is arranged bearing-mountedin device 1 so that it can rotate. A plurality of knives 3 is arrangedon rotor shaft 2, as will be described in more detail below. Device 1 isalso provided with a housing 12 in which a hatch 13 is arranged. Openingthe hatch 13 makes rotor shaft 2 accessible, for instance for thepurpose of replacing components of rotor shaft 2.

FIG. 2 shows a part of rotor shaft 2 of FIG. 1 in detail. Rotor shaft 22is connected to the frame. Fixedly connected to rotor shaft 22 areconnecting discs 4 extending perpendicularly of axis A of rotor shaft22. Connecting discs 4 are embodied as round plates welded onto rotorshaft 22. Three knives 3 are arranged per connecting disc 4, whereinknives 3 are distributed evenly over peripheral edge 41 of discs 4.Knives 3 protrude beyond these peripheral edges 41 and lie more or lessin the plane of connecting discs 4.

Referring to FIG. 3, a knife 3 is provided with a sharp part or blade 31and a connecting end 32 taking a flat or plate-like form. Two connectingholes 33 a and 33 b are arranged in this outer end 32, wherein the hole33 a closest to blade 31 has a larger diameter than the hole 33 b closeto the outer end. Outer end 32 of a knife 3 is moreover provided with arecess so that a sloping contact surface 34 is formed.

Connecting discs 4 are also provided close to their peripheral edge 41with corresponding connecting holes 43 a and 43 b which coincide in theconnected state with the connecting holes 33 a and 33 b of knives 3, seeFIG. 2. Into these holes bolts 73 a and 73 b will later be inserted ontowhich nuts 8 are screwed.

FIG. 3 shows the distribution of the three knives 3 on the connectingdisc, wherein the coinciding holes for connecting knife 3 to disc 4 arevisible. Now that knives 3 do not cover the whole peripheral edge 41 ofdisc 4, filler pieces 5 are arranged which fit precisely onto thecontours of knives 3. The three filler pieces 5 are provided withprojections 51 which fit precisely onto the recess in the plate-likeconnecting end 32 of knives 3 so that they lie against the contactsurface 34 of these knives 3. The other outer end 52 of a filler piece 5takes a flat form so that it can lie against the straight surface 35 ofknife 3.

Filler piece 5 takes the form of a ring sector, wherein outer periphery53 has the same form, i.e. radius, as peripheral edge 41 of disc 4, ascan be seen for arranged filler pieces at the bottom of FIG. 3. Innerperiphery 55 of filler pieces 5 is formed more or less parallel to theouter periphery. The thickness of filler pieces 5, i.e. the thickness inthe direction of axis A, or perpendicularly of the plane of connectingdisc 4, is equal to the thickness of the plate-like outer end 32 of aknife 3. In the connected state of the filler pieces and the knives asshown at the bottom of FIG. 3 the surfaces of knives 3 and filler pieces5 form a substantially flat surface.

For attachment of filler pieces 5 to rotor shaft 2 the filler pieces areprovided with three holes 54 arranged at equal radial distances. Discs 4are also provided with corresponding holes 44 which in the connectedstate coincide with holes 54 of the filler pieces so that bolts 74 canbe placed therethrough, see again FIG. 2. The diameter of holes 44 and54 is smaller than the diameter of holes 33 and 43 for connecting theknives 3.

Ring parts 6 are arranged over the flat surface formed by outer ends 32and filler pieces 5, see in particular FIG. 4. Ring parts 6 fit closelyto each other at the outer ends so as to form an annular structure forattachment of knives 3 and filler pieces 5, wherein knives 3 and fillerpieces 5 are situated between connecting disc 4 and ring parts 6 as seenin the direction of axis A.

A ring part 6 is also provided once again with a larger hole 63 a and asmaller hole 63 b for connecting the knives 3. A ring part 6 isconnected here to two knives 3 so that the one outer end of a ring partcomprises the one hole 63 a while the other outer end comprises theother hole 63 b. A subsequent ring part 6 is then in turn connected tothe other hole 33 a of a knife 3.

In order to provide sufficient strength around the larger hole 63 a ofring part 6, the ring part is provided close to this outer end with aprotrusion 62. This ensures sufficient material round hole 63. Alsovisible is that holes 63 a and 63 b are located at different radialdistances. Also present once again between holes 63 for receiving bolts73 for connecting the knives 3 are holes 64 for receiving bolts 74 forconnecting the filler pieces 5. Holes 44 in the connecting disc, holes54 in filler pieces 5 and holes 64 in ring parts 6 coincide here andhave corresponding diameters. The same applies for holes 43 a, 53 a and63 a and 43 b, 53 b and 63 b. The outer periphery 65 of a ring part 6again corresponds to the shape of peripheral edge 41 of disc 4 and theinner periphery 66 of a ring part 6 corresponds to inner periphery 55 ofa tiller piece 5, so that tiller pieces 5 are substantially whollyoverlapped by a ring part 6 in the connected state, as can also be seenat the bottom of FIG. 4, in which the connected state is shown.

As stated, bolts 73 and 74 are arranged through the coinciding holes andnuts 8 are then screwed thereon. An efficient connection of knives 3 torotor shaft 2 is thus obtained which can moreover be released in simplemanner if a component of the rotor shaft is damaged.

The present invention is not limited to the shown embodiments but alsoextends to other embodiments falling within the scope of the appendedclaims.

The invention claimed is:
 1. A rotor shaft for use in an aerating devicefor a ground, wherein the rotor shaft comprises: at least one connectingdisc which extends transversely of the axis of the rotor shaft and onwhich at least two knives are arranged, wherein each knife is providedwith two knife connecting holes and is connected between the connectingdisc and a connecting ring, wherein the connecting disc and theconnecting ring are provided with knife connecting holes which coincidewith the knife connecting holes of the knives, wherein bolts arearranged through the coinciding knife connecting holes in order toconnect the connecting disc, the knives and the connecting ring, whereinthe rotor shaft further comprises ring sector-shaped filling membersbetween the knives, wherein a filling member has a form such that itfills on the one hand the space between the connecting disc and theconnecting ring and on the other hand the space between two knives. 2.The rotor shaft as claimed in claim 1, wherein a filling member isprovided with at least one filling member connecting hole and whereinthe connecting ring and connecting disc are provided with filling memberconnecting holes which coincide with the filling member connecting holesof the filling members, wherein bolts are arranged through thecoinciding filler piece connecting holes in order to connect theconnecting disc, the filling members and the connecting ring.
 3. Therotor shaft as claimed in claim 1, wherein the filling members and theknives form a continuous annular structure in the connected state,wherein the knives are held in form-fitting manner between the fillingmembers, the connecting disc and the connecting ring.
 4. The rotor shaftas claimed in claim 1, wherein a knife is provided with a recess whichforms a contact surface with a normal with a component in the radialdirection, wherein a filling member is provided with a projection with aform complementary to the contact surface of the recess.
 5. The rotorshaft as claimed in claim 4, wherein the projection is arranged at anouter end of a filling member.
 6. The rotor shaft as claimed in claim 2,wherein the filling member connecting holes have a diameter differingfrom that of the knife connecting holes.
 7. The rotor shaft as claimedin claim 1 , wherein the connecting ring is constructed from at leasttwo ring sectors which together form the connecting ring.
 8. The rotorshaft as claimed in claim 7, wherein the ring sectors are uniform. 9.The rotor shaft as claimed in claim 7, wherein each ring sector isprovided close to the outer ends with a knife connecting hole, wherein aring sector is connected to two knives and extends therebetween.
 10. Therotor shaft as claimed in claim 1, wherein the knife connecting holesfor a single knife are located at different radial distances, wherein aring sector is provided with at least one protrusion for accommodating aknife connecting hole.
 11. A ring sector-shaped filling member having aform such that it fills on the one hand a space between a connectingdisc and a connecting ring and on the other hand a space between twoknives of a rotor shaft according to claim
 1. 12. An aerating device fora ground, the device comprising: a frame; moving means arranged on theframe for the purpose of moving the aerating device in a direction ofmovement over a surface for working; a drive; and a rotor shaft asclaimed in claim 1 operatively connected to the drive for the purpose ofrotating the rotor shaft.
 13. The aerating device as claimed in claim12, further comprising a housing which protects at least the rotorshaft, wherein the housing is provided with a hatch which is arrangedhingedly on the housing for the purpose of making the rotor shaftaccessible.